Earth Today | Seagrass: Unsung hero of Caribbean blue carbon

SEAGRASS BEDS are the nurseries of our ocean, the first home of the snapper, grunt, and parrotfish that sustain coastal livelihoods across the Caribbean; and the primary food source for green sea turtles and West Indian manatees.

Seagrasses are flowering plants and are among the most productive ecosystems on Earth. Not only do seagrass beds provide nursery habitat supporting more than 20 per cent of the world’s largest 25 fisheries, they are estimated to be up to 40 times more efficient at capturing carbon than land forest soil, locking it away in sediments over centuries and millennia. Carbon that is captured and stored by coastal and marine ecosystems is known as blue carbon.

Research from the Colombian Caribbean, published in Scientific Reports in 2025, found that seagrass beds sequester carbon at a rate equivalent to roughly 0.4 per cent of Colombia’s total annual fossil fuel emissions – figures that are increasingly relevant as Caribbean governments build their national climate commitments. In The Bahamas, a 2023 study published in Communications Earth & Environment estimated that Bahamian seagrass beds store between 420 and 590 million tons of organic carbon in the top metre of sediment alone. That is an extraordinary carbon store sitting in the shallow waters of a single Caribbean nation.

The regional picture, however, is one of accelerating loss. A long-term study monitoring 52 seagrass stations found that 43 per cent of communities showed changes in biomass and productivity associated with environmental degradation, with agricultural and sewage runoff identified as the primary cause. Since 2011, the annual influx of pelagic Sargassum seaweed, driven by warming Atlantic waters and nutrient runoff, has added a compounding threat, smothering nearshore seagrass zones across multiple island states. A 2025 global synthesis published in Nature Communications estimated that seagrass carbon stocks at risk of degradation could emit the equivalent of 1,154 million tons of CO2 if left unprotected, carrying a social cost of USD 213 billion.

Seagrass has rarely featured in Caribbean conservation policy with the same urgency given to coral reefs and mangroves, yet the evidence tells us that it belongs in the same conversation. Protecting seagrass beds means protecting the fisheries that feed our communities, the carbon stores that count toward our climate commitments, and the coastal buffers that stand between vulnerable coastlines and an increasingly hostile ocean. The Caribbean region cannot afford to overlook them any longer.

Contributed by Renée Smith, communications officer, Caribbean Biodiversity Fund